Dishwashing



. EDGAR S. STODDARD, OF BERWYN, ILLINOIS, ASSIGNOR OF CHICAGO, ILLINOIS, A CORPORATION Patented Aug. 9, 1932 UNITED STATES PATENT OFFICE TO THE CONOVER COMPANY, OF ILLINOIS DISHWASHING No Drawing. Application filed June 24,

This invention relates to an improved method of utilizing liquid containing machines, such as dishwashing machines, and it particularly relates to an improved process of washing and cleansing dishes, cups, plates, glasses and so forth in connection with a dishwashing machine.

Although the present invention is adapted to be utilized in connection with the washing and cleansing of dishes, plates, cups, glasses, sauce'rs and similar objects in dishwashing machines generally, it will be specifically described as applicable to the washing and cleansing operations as carried out in dishwashing machines of the spray-pro jector type.

In these machines a fine spray of the cleansing liquid, which is usually water, containing soapv or some other detergent, is projected against the surface of the object to be cleansed at the rate of about 2,000 to 3,000 feet per minute, thus causing a considerable impact when the water strikes the object. This impact in addition to the washing action of the water, is effective to loosen and carry away the food and dirt particles adhering to the objects being cleansed. An object of the present invention is to provide an improved process of cleansing dishes, plates, bowls, saucers, cups, and similar objects so that it will be unnecessary to subject such objects to manual cleansing or washing operations.

Another object of this invention is to provide an improved manner of operating a dishwashing machine, especially of the sprayprojector type.

A further object is to provide an improved process by means of which objects may be effectually cleansed in dishwashing machines of the spray-projector type.

Other objects will appear during the course of the following specification.

Spray-projector type dishwashing machines in connection with which the process of the present invention may be utilized are more fully shown and described in applica- 1929. Serial No. 873,483.

screw propeller-like impeller, wit-h curved blades, which impeller rotates at a high velocity of the order of 1,000 to 2,000 R. P. M. in the lower part of the tank of the machine. Only the lower part of this impeller is immersed in the shallow liquid pool in the lower part of the tank. The shallow liquid pool in the lower part of the machine is maintained in relatively quiescent condition during the operation of the machine. As it turns, the impeller elevates the liquid from its lower screw propeller'portions to its upper concave projectors which throw the cleansing liquid at a high velocity directly upon, or into, the objects to be cleansed. Since there are no bafiies or deflectors to break the force of the liquid, the total force of the projected mass of liquid is effective for cleansing purposes. Although the velocity of the cleansing liquid is very high, the volume of cleansing liquid is very small, andas a result a very effective cleansing is obtained with a minimum and most eflicient use of the cleansing agent.

As a specific example of the practicing of the processes of the present invention, the operation of cleansin dishes and similar objects in a spray-pro ector type dishwashing machine, such as those described in the above identified applications, will be described. Dishwashing machines of the spray-projector type are provided with verwater, which pool may be of increased depth below the central portion of the water actuating device. The deepest portion of such pool may be adapted toreceive all the incoming and circulating washing and rinse liquids before they are taken up and distributed by the impeller or water actuating device, and it also is adapted to receive all waste liquid before it is discharged from the tank.

The Washing chamber is adapted to be opened either on the top or side, and by means of such opening it may be filled with the objects to be cleansed. In the preferred embodiment of the invention, the dishes,

plates and silverware are positioned vertically in the lower part of the washing chamber above the liquid pool and the impeller. In the case of the silverware, the portions which come into contact with the food are positioned uppermost, while in the case of dishes and plates, the concave portions are caused to face the center of the machine either partly or wholly. The upper part of the washing chamber is adapted to contain the deep vessels such as the glasses, cups, deep bowls, etc. These articles are positioned so as to face the impeller or the lower center of the washing machine. When the dishes have been put into posit-ion in the washing chamber, the washing chamber is closed. The washing chamber is provided with suitable vents which will permit the movement of vapors into or out of the washing chamber, but such vents are well bafiled so as to prevent the movement of any moisture or spray from the washing chamber to the outside of the machine. In a preferred embodiment of the invention, before the washing chamber is closed, a suitable amount of a detergent is placed within the washing chamber, most desirably upon the water actuating device or the impeller. It is ordinarily preferable, with not quickly soluble detergents, that none of the detergent material be placed upon the dishes or other objects within the washing chamber. A most satisfactory detergent for this purpose is a foaming detergent such as a water soluble soap or an alkali metal salt of a high molecular weight fatty acid and as a general rule it is desirable to use about 1 to 5 tablespoonfuls of such a soap to every5 quarts of liquid. This amount is primarily adapted to soap when used in flake form. If the soap is utilized in some other formsequivalent proportions should be used.

The desired amount of cleansing or washing liquid is then added to the washing chamher. As stated above, it may be preferable to form a liquid pool which is of increased depth under the impeller or water actuating device. The machine is most desirably constructed so that the liquid may be introduced without opening the washing chamber. The

\ water or other liquid should preferably be too hot to touch. The temperature may be materially over 140 F. It is usually not over about 210 F. The normal charge for a dish-washing machine will vary between 2 to 15 quarts of liquid, depending upon the size of the washing chamber and actuating device. To this water, before or just after being placed int-he washing chamber, is preferably added a non-sud-producing or non-colloidal soluble alkaline reacting alkaline earth or alkali metal salt. This agent may have some detergent value and will preferably not cause the formation of substantial quantities of suds or foam.

A satisfactory material of this character is trisodium phosphate. About one-half to three tablespoons of this material of this character is added to the water placed in the machine. The proportions of this material are adjusted to the requirements of the local water supply and the amount of water placed in the washing chamber.

The water actuating device may be put into motion before the hot water is added. By setting the impeller or water actuating device in rotation before adding the cleansing liqaids, the starting torque required of the motor is reduced and the tendency for the evolution of large volumes or sudden rushes of steam, which might cause lifting of the lid and upsetting of the glassware and dishes, may be practically eliminated. The relatively slow addition of liquid to the rotating impeller is therefore preferable to the sudden initiation of rotation when the impeller is immersed to its normal static level. The charging of the machine with a measured volume of Cleansing liquid, while the impeller is in rotation, moreover enables the saving of time.

As stated above, the amount of foaming detergent utilized will vary between 1 to 5 tablespoonfuls of soap flakes for every 5 quarts of water. Preferably about 1 to 1% tablespoonfuls are most satisfactorily employed. The concentration of soap should be such that the cleansing liquid has sufficient viscosity and froth to emulsify and/or sup port the grease and food particles to be removed from the dishes and carried out of the machine. The washing and cleansing liquid during operation of the machine may have the consistency of whipped cream. Soapsuds of this consistency reduce the slight noise of the circulating water in the machine. 7 If there is a noticeable increase of the sound of the Water during the washing operation, it is a sign that insufficient soap was added or that more soap is necessary. In the latter case the water actuating device should be stopped, the washing chamber should be opened and more soap added. The amount of soap required is generally proportional to the amount of water and the amount of grease upon the dishes. If the dishes and other objects are very greasy, more soap is required to emulsify the same. It is undesirable, however, to have too much soap in the machine for in such a case the suds will become very thick, will interfere with the spray-projection operation and will not be easily removed from the machine. In case there is such a large quantity of suds as will. prevent ready removal of the waste fluids from the washing chamber, it is desirable to allow additional hotwater to enter the washing chamber so as to dilute the suds before discharging the machine.

After the machine has been charged and the water actuating device set into motion, the dishes are allowed to wash for a-period between about 3 to 10 minutes, say 5 minutes. After this period the wash water is discharged without opening the washing chamber and the tank is again charged with hot liquid. About the same amount of liquid of about the same temperature as before is utilized. To this liquid is preferably added the same quantity of alkaline reagent as was utilizedin the washing operation. The machine is then allowed to operate for between one-half to 2 or 3 minutes, say about one minute,and,the machine is again discharged of liquid. The machine is then a second time charged with a rinsing liquid (preferably clear hot water) of about the same temperatureand in the same amount as previously EDGAR S. STODDARD.

described, and the operation is allowed to continue for about the same period as in the previous operation. In this second rinsing operation no alkaline reagent is added to the water unless such-water is extremely hard.

Whenithe machine is again discharged, the washing chamber is full opened to, the atmosphere, and air is a lowed to circulate throu h the machine to dry the articles therein. I water of theproper temperature has been utilized, the dishes willdry by evaporation in a very short time.

In the preferred operation of the machine, the water actuating device is kept in motion during the charging, discharging cleansing and rlnsing operations. The washing chamber of the machine is also preferably kept closed during these operations. 1

Although trisodium phosphate is the preferred non-colloidal alkaline reagent and soap is the preferred foaming detergent because of their availability in most households, it is obvious that other equivalent rea nts or detergents may be readily utilized. or example, it is possible to utilize alkaline-reacting alkali metal or alkaline earth salts in place of or in addition to trisodium phos- I 7 the dishes with hot water.

phate. It is also possible to use other sud- 1 2, A method of cleansing dishes which.

60 comprises forming a solution of soap and trisodium phosphate in a quantity of hot water, forcibly projecting the water with said materials therein in the form of a spray against the dishes to be cleaned, preparin a second 35 solution of trisodium phosphate in ct water, 

